home_url(), 'return' => add_query_arg( 'page', 'mission-options', admin_url( 'themes.php' ) ) ), admin_url( 'customize.php' ) ); ?>

...

Warning: Clicking this button will erase the %2$s theme\'s current settings in the Customizer.', 'mission-news' ), esc_url( $customizer_url ), esc_attr( wp_get_theme( get_template() ) ) ); ?>